The placental adhesive disorders such as placenta accreta and placenta percreta are the rare causes of serious obstetric hemorrhages. They are associated with high maternal morbidity and mortality. Placenta percreta is usually diagnosed in the third trimester of pregnancy as a massive postpartum hemorrhage when an attempt to remove the placenta reveals lack of a cleavage plane. Here we report an unusual presentation of placenta percreta as hemoperitoneum and hemorrhagic shock in the third trimester of pregnancy. A 33-year-old woman was admitted to hospital at the 35th weeks of gestation with abdominal pain and hemorrhagic shock. Laparotomy was immediately performed because of intra-abdominal bleeding. Upon inspection, a posterior laceration of the uterus was noted. Pathologic investigation of the uterus showed placenta percreta. The patient recovered uneventfully. Spontaneous rupture of the uterus can be occured in the absence of uterine trauma. In the differential diagnosis of a pregnant woman presenting with hypotension, abdominal pain, and fetal death, rupture of the uterus caused by placenta percreta should be considered. Rapid diagnosis, blood transfusion, and emergency laparotomy are the key steps in successful management.